Apparatus for guiding a foil web

ABSTRACT

A foil web of indefinite length is advanced in a taut condition along one part of its path of travel by a series of jaws clamped along both lateral edges of the web. The jaws are attached to the links of two endless chains disposed at either side of the web. Those terminal sprockets of the two chains that are at the run-in location of the web are slightly inclined to one another, so that the distance between the two said sprockets at the run-in side of the chains is slightly larger than at the run-off side. Between the two said sprockets there is rotatably held a web guiding drum which positions the running web at the height of the jaws as they run off the sprockets at the run-in side of the web.

United States Patent 1 Grebe June 12, 1973 APPARATUS FOR GUIDING A FOIL WEB Primary Examiner-Allen N. Knowles [75] Inventor: Ludwig Grebe, Wallau/Lahn, Ass'smm Examfner cel le Church Germany Attorney-Edwm E. Grelgg [73} Assignee: Kramer & Grebe, KG Maschinen und Modellfabrik, Wallau/Lahn, [571 ABSTRACT Germany A foil web of indefinite length is advanced in a taut [22] Filed; May 10, 1972 condition along one part of its path of travel by a series of jaws clamped along both lateral edges of the web. PP N05 251,915 The jaws are attached to the links of two endless chains disposed at either side of the web. Those terminal [30] Foreign Application Priority Data sprockets of the two chains that are at the run-in loca- M 11 1971 Get an P 21 23 133 4 tion of the web are slightly inclined to one another, so ay m y that the distance between the two said sprockets at the run-in side of the chains is slightly larger than at the rumoff Side. Between the two Said Sprockets there is ro [58] Fie'ld 3 tatably held a web guiding drum which positions the 53/l running web at the height of the jaws as they run off the sprockets at the run-in side of the web. [56] UNITE S A E s g:rENTS 2 Claims, 2 Drawing Figures 3,673,760 7/1972 Canamero et al. 226/173 X 3,469,819 9/1969 Puretic 226/172 APPARATUS FOR GUIDING A FOIL WEB BACKGROUND OF THE INVENTION This invention relates to a device for guiding a foil web in packaging machines by means of jaws engaging the web along both lateral edges. The jaws are carried by the links of two parallel spaced endless chains and travel in such a manner that each jaw, as its associated chain link runs on the terminal sprockets, approaches laterally the immediately adjacent edge of the running web.

Devices of the aforeoutlined type, such as disclosed, for example, in U.S. Pat. Nos. 3,517,479 and 3,286,817, require substantial space because the planes of the sprockets extend parallel to the plane of the advanced web. Thus, the rotational axes of the sprockets are at a greater distance from one another and are disposed normal to the plane of the web at the two sides thereof. It necessarily follows that such a'device requires a greater number of guide rollers for each chain and its driving means is relatively complex.

According to another known device, the chain sprockets are arranged parallel to one another at the run-in location of the web (thus, the planes of the sprockets are disposed normal to the web plane). Consequently, the upper flights of the two chains are at the same distance from one another as the distance be tween the two lower flights. The foil web to be engaged first runs with both edges onto the open clamping jaws and then it is guided by appropriate deflecting rollers in such a manner that the web edges are bent upwardly, whereupon they snap into the open jaws. This manner of introducing the web into the open jaws carried by the chains involves the deformation of the web which is possible only in case of thin foils. In case of thicker foils such an introduction of the edges into the jaws becomes difficult if not impossible since a deformation of the edges. is resisted by the thicker foil. If the bending force is large enough, the edges would tear inwardly.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to eliminate the disadvantages in the aforenoted two types of known devices and, on the one hand, to effect a slow approach of the chain links to the foil web and, on the other hand, to provide a structure which in simplicity is comparable to the last-described known device.

Briefly stated, according to the invention, at the runin side of the foil web, the sprockets of the two chains are disposed inclined with respect to one another in such a manner that the distance between the two parallel chains at the run-in locations on the sprockets is relatively only slightly larger than the distance between the chains at the run-out locations on the sprockets. Further, between the inclined sprocket wheels there is rotatably supported a web guiding drum, the cylindrical surface of which guides the foil web along a path similar to that of the jaws.

The slight torsion of each chain due to the inclined position of the chain sprockets at the run-in side of the web with respect to the parallel arranged chain sprockets at the run-out side is negligible because of the large distance between the two spockets supporting each chain.

The invention will be better understood as well as further objects and advantahes become more apparent from the ensuing detailed specification of a preferred,

although exemplary embodiment of the invention, taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial sectional view of the preferred embodiment at the run-in side of the web and FIG. 2 is a schematic side elevational view of the same embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the Figures, on parallel arranged frames 1 and la chain sprockets 2, 2a and 17, 17a are rotatably held. The sprockets 2 and 17 support and drive an endless roller chain 18, while the sprockets 2a and 17a support and drive an endless roller chain 18a. The upper flight 20 of the chain 18 extends parallel to the upper flight 21 of the chain 18a, while the lower flight 22 of the chain 18 extends parallel with the lower flight 23 of the chain 180. The chains 18, 18a carry, respectively, a series ofjaws 6, 6a which are biased closed by associated springs and opened by the teeth of the sprockets. These jaws hold a foil web 5 at its edges so that the latter is maintained in a taut condition between the parallel upper flights 20, 21.

The sprocket wheels 2 and 2a arranged at the run-in side of the device are held in an overhung position on shafts 3 and 3a by means of ball bearings 4. The shafts 3 and 3a are inclined at a fixed angle with respect to the horizontal so that the sprocket wheels 2 and 2a, in the lower range where the slack lower chain flight 22 or 23 arrives into engagement with the respective sprocket, have a greater distance from one another than in the upper range from which the upper chain flights 20 and 21 run off with the tensioned foil web therebetween. Stated differently, each sprocket wheel 2, 2a is arranged at a small angle with respect to a plane that is normal to the web 5 in the zone of the sprocket wheels and is parallel to the direction of web travel. In case of a sprocket diameter of mm, the aforenoted angle is advantageously about 4. It is to be understood that the magnitude of this angle is an inverse function of the sprocket diameter to ensure that regardless of the dimensions of the sprocket wheel selected, the clearance between the lower portion of either sprocket wheel 2, 2a and the edge of the web 5 and the extent of its pro jection into the upper portion of either sprocket wheel 2, 2a do not change.

A foil web guiding drum 7 is freely rotatably held by a shaft 8 between the chain sprockets 2 and 2a. The drum 7 has a diameter so designed that the foil web is maintained at the height of those angle members 19, 19a of the jaws 6 and 6a which are momentarily on the upper flights 20, 21.

Turning now to FIG. 2, the foil web pulled from a supply reel 9 is guided over deflecting rollers 10 and I l and is tensioned by a roller 24 supported on a swinging arm 12. The latter is pivotally held on a shaft 13, which also carries the supply reel 9. The deflecting rollers 10 and 1 l as well as the supply reel 9 are arranged in such a manner that the foil web 5 runs onto the drum 7 at a run-in location indicated at 14, which is situated approximately at the height the lower chain flights 22, 23 run onto the sprocket wheels 2, 2a. The foil web is thus trained about the drum 7 approximately The foil web 5 brought in the aforedescribed manner between the chains 18 and 18a enters the open jaws 6,

6a as the chains progressively approach the web from both sides. The jaws are closed by means of springs at the run-out location 15 where the chains leave the sprocket wheels 2, 2a. The jaws 6, 6a are again open at the run-in location 16 by means of the teeth of the sprockets 17, 17a extending into the chains. Thus, the foil web 5, after running through a deep drawing packing machine, is released from the chains. The jaw mechanism and its cooperation with the sprocket teeth is disclosed in detail in German Published Pat. Application No. l,92l,809 (DOS).

In case the sprocket wheels 17, 17a which are supported at the run-out side of the device are inclined in the same manner as the sprocket wheels 2, 2a at the run-in side of the device, then not only a torsion of the chains is avoided, but also, the run-off of the edges of the foil web from the jaws 6, 6a is facilitated.

What is claimed is:

1. In an apparatus for guiding a running foil web of indefinite length in a taut condition along a portion of its path of travel, said apparatus being of the known type that has (a) two endless chains disposed and driven along either lateral edge of said web, each chain having two flights, the corresponding flights in the one and in the other chain running parallel to one another and (b) a plurality of jaws carried by each chain and engaging the adjacent edge portion of the running web at the run-in or upstream end of the apparatus and releasing said edge portion at the run-out or downstream end of the apparatus, the improvement comprising A. two first and two second sprockets, each chain being trained about and supported by a first and a second sprocket, said first sprockets being arranged at the upstream end of said apparatus and each being inclined at a small angle with respect to a plane that is normal to the plane of said web and parallel to its direction of travel, the distance between said chains at the location of take-up on said first sprockets being relatively slightly larger than the distance between said chains at the location of run-off from said first sprockets, said second sprockets being arranged at the downstream end of said apparatus and B. a foil web guiding drum rotatably supported between said first sprockets and engaging said running web, said drum being so oriented as to guide said running web along the path of travel of said jaws. 2. An improvement as defined in claim 1, wherein said second sprockets are arranged at an inclination identical to that of said first sprockets. 

1. In an apparatus for guiding a running foil web of indefinite length in a taut condition along a portion of its path of travel, said apparatus being of the known type that has (a) two endless chains disposed and driven along either lateral edge of said web, each chain having two flights, the corresponding flights in the one and in the other chain running parallel to one another and (b) a plurality of jaws carried by each chain and engaging the adjacent edge portion of the running web at the run-in or upstream end of the apparatus and releasing said edge portion at the run-out or downstream end of the apparatus, the improvement comprising A. two first and two second sprockets, each chain being trained about and supported by a first and a second sprocket, said first sprockets being arranged at the upstream end of said apparatus and each being inclined at a small angle with respect to a plane that is normal to the plane of said web and parallel to its direction of travel, the distance between said chains at the location of take-up on said first sprockets being relatively slightly larger than the distance between said chains at the location of run-off from said first sprockets, said second sprockets being arranged at the downstream end of said apparatus and B. a foil web guiding drum rotatably supported between said first sprockets and engaging said running web, said drum being so oriented as to guide said running web along the path of travel of said jaws.
 2. An improvement as defined in claim 1, wherein said second sprockets are arranged at an inclination identical to that of said first sprockets. 